We are not historians. What follows is our interpretation of what we read and learned. We set it down so we can carry it with us and review it as we travel across Britain and Ireland.

This primer tells the history of Great Britain and Ireland in broad strokes, from the Iron Age to 1922. It is not a textbook. It is a companion for the road, with enough history to make sense of the walls, castles and ruins we visit and the names we meet along the way.

Today the islands hold two states: the Republic of Ireland, and the United Kingdom of England, Scotland, Wales and Northern Ireland. For most of this story none of these countries existed, so the early sections speak of “the area of modern Scotland” and so on, only as a guide on the map. Ireland is told side by side with Britain. For more than a thousand years it had its own kings, laws and church, until Norman knights from Wales landed there in 1169.

The primer has four parts:

• Part One: from the Iron Age to 793, when the Vikings attacked Lindisfarne.
• Part Two: the Vikings and the making of kingdoms, 793 to 1066.
• Part Three: the Normans and the medieval kingdoms, 1066 to 1485.
• Part Four: crowns, unions and separation, 1485 to 1922.

A large archipelago lies off the northwest coast of mainland Europe. It is composed of two main islands (Island of Great Britain and Island of Ireland) and thousands of smaller islands surrounding them. The Atlantic Ocean lies to the west and north. The North Sea lies to the east, between Great Britain and Norway, Denmark, Germany, the Netherlands and Belgium. To the south, the English Channel separates Great Britain from France. At its narrowest point, the Strait of Dover, the Channel is about twenty one miles wide. The Irish Sea separates the two larger islands. The Celtic Sea lies to the south, between the southern coast of Ireland and the southwestern tip of Great Britain.

Five countries share these islands. Three smaller islands, the Isle of Man, Jersey and Guernsey, govern themselves and are not part of any of the five. Many names are used for all of these, and some of the names sound alike but cover different areas and have different meanings. This primer explains what each name includes today. It also shows how they are grouped in international organizations, in sport, in money and in travel. History and politics are not the topic of this post.